1. Field of the Invention
The present invention relates to a magnetic sensor.
2. Related Background Art
A magnetoresistive element is known as a magnetic sensor used in a thin-film magnetic recording/reproducing head or the like. In the magnetoresistive element, generally, an electric current is made to flow between a magnetization fixed layer and a magnetization free layer, thereby obtaining a high output. However, the magnetoresistive element produces a signal unnecessary for the magnetic sensor, which is caused, for example, by domain wall displacement due to spin torque given by the electric current.
Another known magnetic sensor is a Spin Accumulation (SA) magnetic sensor in which the magnetization free layer and the magnetization fixed layer are formed on an identical horizontal surface (channel layer for spin accumulation) (e.g., cf. Patent Document 1 and Patent Document 2). For example, when the spin accumulation magnetic sensor is used in the thin-film magnetic recording/reproducing head, there is no need for flowing an electric current to the magnetization free layer for sensing an external magnetic field of a magnetic recording medium or the like. Namely, the spin accumulation magnetic sensor can detect a magnetic state as an output voltage by making use of only the spin current. Therefore, there is no risk of observation of the unnecessary signal, which was observed in the magnetoresistive element, in the spin accumulation magnetic sensor.    Patent Document 1: Japanese Patent Application Laid-open No. 2007-299467    Patent Document 2: Japanese Patent No. 4029772